Advancements in surgical procedures and development of novel immunosuppressive strategies have fortunately led to increased survival among recipients of solid organ transplants. It is known that individuals with compromised immune systems are at increased risk of certain cancers. However, it is not clear whether cancer among transplant recipients is solely the result of a compromised immune response, or whether the cytotoxic effects of the immunosuppressive agents themselves may result in increased DNA damage and possibly carcinogenesis. The overall goal for this project is to provide greatly needed information about cancer incidence among solid organ transplant recipients in the US. The following specific aims are proposed to accomplish the overall goal of this project: (1) Link population-based registry data from the National Cancer Institute's Surveillance, Epidemiology and End Results program and the Scientific Registry of Transplant Recipients to identify all individuals who were diagnosed with cancer following whole organ transplantation in California, Iowa, the Seattle/Puget Sound area and the Detroit Metropolitan area between 1990 and 2001; (2) Calculate age-adjusted standardized incidence ratios, for overall and site-specific cancers, by comparing observed incidence among individuals who received whole organ transplants, to expected incidence among the general population; and, (3) Conduct survival analysis of age at cancer diagnosis among transplant recipients. This project proposes to analyze previously collected data for epidemiologic purposes that are relevant to cancer etiology, which may lead to cancer control and prevention investigations, in direct response to the Program Announcement for Small Grants in Cancer Epidemiology. Only recently in the US have the available data been robust, complete or of high enough quality to calculate stable population-based estimates of cancer incidence among transplant recipients. The identification of cancers with higher incidence among transplant recipients, compared to the general population is novel, timely and has direct impact on the long-term objective of reducing cancer incidence among this uniquely susceptible and emergent population.